max / makeover

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1	//! Shared theme loading + intent resolution for TOML-based theme files.
2	//!
3	//! Used by GoingsOn, Balanced Breakfast (Tauri apps), audiofiles (egui), and the
4	//! MNW web server. Themes are authored by intent ("human design"): colors are
5	//! declared by role (surface / content / action / status / line / category), not
6	//! by hue. This crate is the single place that resolves an authored theme into a
7	//! full set of intent tokens — including the derived interactive states
8	//! (hover/active/selection/row-stripe/contrast) that each app used to recompute
9	//! itself — and emits them as CSS variables or RGB tuples.
10	//!
11	//! Theme file shape:
12	//! ```text
13	//! [meta]
14	//! name = "Nord"
15	//! variant = "dark" # or "light"
16	//!
17	//! [surface] # container backgrounds by role/elevation
18	//! page = "#2e3440"; raised = "#3b4252"; sunken = "#434c5e"; overlay = "#3b4252"
19	//!
20	//! [content] # text/ink by emphasis
21	//! primary = "#d8dee9"; secondary = "#e5e9f0"; muted = "#616e88"
22	//!
23	//! [action] # interactive / brand color
24	//! primary = "#81a1c1"
25	//!
26	//! [status] # state semantics
27	//! danger = "#bf616a"; success = "#a3be8c"; warning = "#ebcb8b"; info = "#88c0d0"
28	//!
29	//! [line]
30	//! border = "#4c566a"
31	//!
32	//! [category] # distinct decorative colors for tags/badges/charts
33	//! one = "#bf616a"; two = "#a3be8c"; three = "#81a1c1"
34	//! four = "#ebcb8b"; five = "#b48ead"; six = "#88c0d0"
35	//! ```
36
37	// Color-space math: single-letter channel names (r/g/b/l/m/s) and the published
38	// high-precision OKLab/sRGB matrix constants are the domain vocabulary here.
39	#![allow(clippy::many_single_char_names, clippy::unreadable_literal)]
40
41	use serde::Serialize;
42	use std::collections::{BTreeMap, HashMap};
43	use std::path::{Path, PathBuf};
44
45	/// The color sections an authored theme may declare.
46	pub const COLOR_SECTIONS: &[&str] = &["surface", "content", "action", "status", "line", "category"];
47
48	/// Theme metadata parsed from the `[meta]` section.
49	#[derive(Debug, Clone, Serialize)]
50	#[serde(rename_all = "camelCase")]
51	pub struct ThemeMeta {
52	pub id: String,
53	pub name: String,
54	pub variant: String,
55	pub is_custom: bool,
56	}
57
58	/// A loaded theme: metadata plus the authored colors, flattened to dotted keys
59	/// (e.g. `"surface.page"`, `"status.danger"`, `"category.one"`).
60	#[derive(Debug, Serialize)]
61	#[serde(rename_all = "camelCase")]
62	pub struct ThemeColors {
63	pub meta: ThemeMeta,
64	pub colors: HashMap<String, String>,
65	}
66
67	// ============================================================================
68	// Color math — perceptual (OKLab) derivations + WCAG contrast.
69	//
70	// Interactive states (hover/active/selection/surfaces) are derived in OKLab so
71	// equal steps look equal across every theme's hues (Ottosson 2020; the modern
72	// CIELAB). Text-on-color is picked by the WCAG 2.x contrast ratio, not a naive
73	// luminance threshold, so the choice actually meets AA where achievable.
74	// This is the single source of truth shared by every product.
75	// ============================================================================
76
77	/// An sRGB color. Hex round-trips losslessly.
78	#[derive(Clone, Copy, Debug, PartialEq, Eq)]
79	pub struct Rgb {
80	pub r: u8,
81	pub g: u8,
82	pub b: u8,
83	}
84
85	impl Rgb {
86	/// Parse `#rgb` or `#rrggbb` (case-insensitive). Returns `None` otherwise.
87	pub fn from_hex(s: &str) -> Option<Rgb> {
88	let h = s.strip_prefix('#')?;
89	let (r, g, b) = match h.len() {
90	6 => (
91	u8::from_str_radix(&h[0..2], 16).ok()?,
92	u8::from_str_radix(&h[2..4], 16).ok()?,
93	u8::from_str_radix(&h[4..6], 16).ok()?,
94	),
95	3 => {
96	let d = \|c: &str\| u8::from_str_radix(c, 16).ok().map(\|v\| v * 17);
97	(d(&h[0..1])?, d(&h[1..2])?, d(&h[2..3])?)
98	}
99	_ => return None,
100	};
101	Some(Rgb { r, g, b })
102	}
103
104	/// Lowercase `#rrggbb`.
105	pub fn to_hex(self) -> String {
106	format!("#{:02x}{:02x}{:02x}", self.r, self.g, self.b)
107	}
108
109	pub fn tuple(self) -> (u8, u8, u8) {
110	(self.r, self.g, self.b)
111	}
112	}
113
114	/// A color in OKLab (perceptually uniform): `l` lightness in [0,1], `a`/`b` opponent axes.
115	#[derive(Clone, Copy, Debug)]
116	pub struct Oklab {
117	pub l: f32,
118	pub a: f32,
119	pub b: f32,
120	}
121
122	fn srgb_to_linear(c: u8) -> f32 {
123	let c = c as f32 / 255.0;
124	if c <= 0.04045 {
125	c / 12.92
126	} else {
127	((c + 0.055) / 1.055).powf(2.4)
128	}
129	}
130
131	fn linear_to_srgb(c: f32) -> u8 {
132	let c = c.clamp(0.0, 1.0);
133	let v = if c <= 0.0031308 {
134	c * 12.92
135	} else {
136	1.055 * c.powf(1.0 / 2.4) - 0.055
137	};
138	(v * 255.0).round().clamp(0.0, 255.0) as u8
139	}
140
141	impl Rgb {
142	/// Convert to OKLab (Ottosson's sRGB matrices).
143	///
144	/// The matrix coefficients are quoted at their published precision so they
145	/// can be diffed against the reference. `f32` rounds them at compile time;
146	/// truncating the literals would only make them harder to check.
147	#[allow(clippy::excessive_precision)]
148	pub fn to_oklab(self) -> Oklab {
149	let (r, g, b) = (
150	srgb_to_linear(self.r),
151	srgb_to_linear(self.g),
152	srgb_to_linear(self.b),
153	);
154	let l = 0.4122214708 * r + 0.5363325363 * g + 0.0514459929 * b;
155	let m = 0.2119034982 * r + 0.6806995451 * g + 0.1073969566 * b;
156	let s = 0.0883024619 * r + 0.2817188376 * g + 0.6299787005 * b;
157	let (l_, m_, s_) = (l.cbrt(), m.cbrt(), s.cbrt());
158	Oklab {
159	l: 0.2104542553 * l_ + 0.7936177850 * m_ - 0.0040720468 * s_,
160	a: 1.9779984951 * l_ - 2.4285922050 * m_ + 0.4505937099 * s_,
161	b: 0.0259040371 * l_ + 0.7827717662 * m_ - 0.8086757660 * s_,
162	}
163	}
164
165	/// Convert from OKLab back to the nearest in-gamut sRGB.
166	///
167	/// Published precision, as in [`Rgb::to_oklab`].
168	#[allow(clippy::excessive_precision)]
169	pub fn from_oklab(c: Oklab) -> Rgb {
170	let l_ = c.l + 0.3963377774 * c.a + 0.2158037573 * c.b;
171	let m_ = c.l - 0.1055613458 * c.a - 0.0638541728 * c.b;
172	let s_ = c.l - 0.0894841775 * c.a - 1.2914855480 * c.b;
173	let (l, m, s) = (l_ * l_ * l_, m_ * m_ * m_, s_ * s_ * s_);
174	Rgb {
175	r: linear_to_srgb(4.0767416621 * l - 3.3077115913 * m + 0.2309699292 * s),
176	g: linear_to_srgb(-1.2684380046 * l + 2.6097574011 * m - 0.3413193965 * s),
177	b: linear_to_srgb(-0.0041960863 * l - 0.7034186147 * m + 1.7076147010 * s),
178	}
179	}
180	}
181
182	/// WCAG 2.x relative luminance of an sRGB color.
183	fn rel_luminance(c: Rgb) -> f32 {
184	0.2126 * srgb_to_linear(c.r) + 0.7152 * srgb_to_linear(c.g) + 0.0722 * srgb_to_linear(c.b)
185	}
186
187	/// WCAG 2.x contrast ratio between two colors, in [1, 21].
188	pub fn wcag_contrast(a: Rgb, b: Rgb) -> f32 {
189	let (la, lb) = (rel_luminance(a), rel_luminance(b));
190	let (hi, lo) = if la >= lb { (la, lb) } else { (lb, la) };
191	(hi + 0.05) / (lo + 0.05)
192	}
193
194	/// Pick black or white for legible text on `bg`, by the higher WCAG contrast
195	/// ratio (so the choice meets AA wherever the background allows it).
196	pub fn readable_on(bg: Rgb) -> Rgb {
197	let white = Rgb {
198	r: 255,
199	g: 255,
200	b: 255,
201	};
202	let black = Rgb { r: 0, g: 0, b: 0 };
203	if wcag_contrast(white, bg) >= wcag_contrast(black, bg) {
204	white
205	} else {
206	black
207	}
208	}
209
210	/// Shift OKLab lightness by `delta` (perceptually uniform). Positive lightens.
211	pub fn lighten(c: Rgb, delta: f32) -> Rgb {
212	let mut lab = c.to_oklab();
213	lab.l = (lab.l + delta).clamp(0.0, 1.0);
214	Rgb::from_oklab(lab)
215	}
216
217	/// Shift OKLab lightness down by `delta` (perceptually uniform).
218	pub fn darken(c: Rgb, delta: f32) -> Rgb {
219	lighten(c, -delta)
220	}
221
222	/// Interpolate between `a` and `b` by `t` in [0,1] in OKLab (perceptual blend).
223	pub fn mix(a: Rgb, b: Rgb, t: f32) -> Rgb {
224	let (x, y) = (a.to_oklab(), b.to_oklab());
225	Rgb::from_oklab(Oklab {
226	l: x.l + (y.l - x.l) * t,
227	a: x.a + (y.a - x.a) * t,
228	b: x.b + (y.b - x.b) * t,
229	})
230	}
231
232	// ============================================================================
233	// Low-color terminals
234	// ============================================================================
235
236	/// The 16 colors an ANSI terminal addresses by index, in the PC/VGA
237	/// arrangement the Linux console and most emulators start from.
238	///
239	/// 0-7 are the normal colors and 8-15 the bright ones. Index 7 is a light gray
240	/// rather than white, which is the entry a themed surface usually lands on, and
241	/// index 15 is the true white.
242	///
243	/// Emulators let the user repaint all sixteen, so this is the standard
244	/// arrangement rather than a promise about any one terminal. The Linux console
245	/// keeps it, which is the case that matters: a console app cannot fall back to
246	/// 24-bit color there.
247	pub const ANSI_16: [Rgb; 16] = [
248	Rgb {
249	r: 0x00,
250	g: 0x00,
251	b: 0x00,
252	},
253	Rgb {
254	r: 0xaa,
255	g: 0x00,
256	b: 0x00,
257	},
258	Rgb {
259	r: 0x00,
260	g: 0xaa,
261	b: 0x00,
262	},
263	Rgb {
264	r: 0xaa,
265	g: 0x55,
266	b: 0x00,
267	},
268	Rgb {
269	r: 0x00,
270	g: 0x00,
271	b: 0xaa,
272	},
273	Rgb {
274	r: 0xaa,
275	g: 0x00,
276	b: 0xaa,
277	},
278	Rgb {
279	r: 0x00,
280	g: 0xaa,
281	b: 0xaa,
282	},
283	Rgb {
284	r: 0xaa,
285	g: 0xaa,
286	b: 0xaa,
287	},
288	Rgb {
289	r: 0x55,
290	g: 0x55,
291	b: 0x55,
292	},
293	Rgb {
294	r: 0xff,
295	g: 0x55,
296	b: 0x55,
297	},
298	Rgb {
299	r: 0x55,
300	g: 0xff,
301	b: 0x55,
302	},
303	Rgb {
304	r: 0xff,
305	g: 0xff,
306	b: 0x55,
307	},
308	Rgb {
309	r: 0x55,
310	g: 0x55,
311	b: 0xff,
312	},
313	Rgb {
314	r: 0xff,
315	g: 0x55,
316	b: 0xff,
317	},
318	Rgb {
319	r: 0x55,
320	g: 0xff,
321	b: 0xff,
322	},
323	Rgb {
324	r: 0xff,
325	g: 0xff,
326	b: 0xff,
327	},
328	];
329
330	/// The 256 colors an xterm-compatible terminal addresses by index, so that
331	/// entry `i` is what the terminal paints for `38;5;i`.
332	///
333	/// Three regions, and they are not equally trustworthy. 0-15 are the [`ANSI_16`]
334	/// system colors, which every emulator lets the user repaint. 16-231 are a
335	/// 6x6x6 RGB cube and 232-255 a 24-step gray ramp, and those 240 are fixed.
336	///
337	/// So a color whose whole job is to be told apart from another should quantize
338	/// against [`ANSI_240`] rather than against this table: a match landing in the
339	/// low sixteen is a match against a color the user may have moved.
340	pub const ANSI_256: [Rgb; 256] = build_ansi_256();
341
342	/// The fixed region of [`ANSI_256`]: the 6x6x6 cube and the gray ramp, without
343	/// the sixteen repaintable system colors.
344	///
345	/// Quantizing against this returns an index into this slice; add
346	/// [`ANSI_240_OFFSET`] to get the index the terminal wants.
347	pub const ANSI_240: &[Rgb] = ANSI_256.split_at(16).1;
348
349	/// What to add to an [`ANSI_240`] index to get an [`ANSI_256`] one.
350	pub const ANSI_240_OFFSET: usize = 16;
351
352	const fn build_ansi_256() -> [Rgb; 256] {
353	let mut table = [Rgb { r: 0, g: 0, b: 0 }; 256];
354
355	let mut i = 0;
356	while i < 16 {
357	table[i] = ANSI_16[i];
358	i += 1;
359	}
360
361	// The cube's six levels are not evenly spaced. The step from black to the
362	// first is more than twice any later one, which is xterm's arrangement
363	// rather than a choice available here, and it is why the darkest tones a
364	// theme can reach on 256 colors come from the gray ramp instead.
365	const LEVELS: [u8; 6] = [0, 95, 135, 175, 215, 255];
366	let mut r = 0;
367	while r < 6 {
368	let mut g = 0;
369	while g < 6 {
370	let mut b = 0;
371	while b < 6 {
372	table[16 + 36 * r + 6 * g + b] = Rgb {
373	r: LEVELS[r],
374	g: LEVELS[g],
375	b: LEVELS[b],
376	};
377	b += 1;
378	}
379	g += 1;
380	}
381	r += 1;
382	}
383
384	// 8 to 238 in steps of 10. Neither end is black or white; both of those are
385	// in the cube, so the ramp is 24 steps of gray between them rather than 24
386	// steps of the whole range.
387	let mut k = 0;
388	while k < 24 {
389	let v = 8 + 10 * k as u8;
390	table[232 + k as usize] = Rgb { r: v, g: v, b: v };
391	k += 1;
392	}
393
394	table
395	}
396
397	/// The contrast ratio two colors must clear to read as separate areas.
398	///
399	/// WCAG 2.x asks 3:1 of user interface components and graphics, which is what
400	/// a border, a rule, or a focus ring is. Text wants more, and a caller drawing
401	/// text can ask for more by checking [`wcag_contrast`] itself.
402	pub const DISTINCT: f32 = 3.0;
403
404	/// Perceptual distance between two colors, for choosing the closest of a set.
405	fn oklab_distance(a: Rgb, b: Rgb) -> f32 {
406	let (x, y) = (a.to_oklab(), b.to_oklab());
407	((x.l - y.l).powi(2) + (x.a - y.a).powi(2) + (x.b - y.b).powi(2)).sqrt()
408	}
409
410	/// Index of the entry in `palette` that looks most like `c`.
411	///
412	/// OKLab distance rather than distance in sRGB, for the same reason [`mix`]
413	/// interpolates there: sRGB's numbers are not spaced the way seeing is, so a
414	/// nearest match computed in it picks visibly wrong entries in the mid tones.
415	///
416	/// # Panics
417	///
418	/// If `palette` is empty.
419	pub fn quantize(c: Rgb, palette: &[Rgb]) -> usize {
420	assert!(!palette.is_empty(), "a palette needs at least one color");
421	let mut best = 0;
422	let mut best_distance = f32::INFINITY;
423	for (index, entry) in palette.iter().enumerate() {
424	let distance = oklab_distance(c, *entry);
425	if distance < best_distance {
426	best = index;
427	best_distance = distance;
428	}
429	}
430	best
431	}
432
433	/// Index of the entry in `palette` closest to `fg` that still reads against
434	/// `bg`.
435	///
436	/// [`quantize`] answers about one color at a time, and two colors that differ
437	/// can quantize to the same entry: a themed page and a border drawn on it are
438	/// often a few steps apart in a 24-bit theme and land together on a 16-color
439	/// terminal, leaving one flat area where there was a frame. Alloy's console
440	/// showed exactly this, and it is not a contrived pairing: a light page and the
441	/// mid-tone border derived from it both land on index 7.
442	///
443	/// So the background is quantized first, because what the border must be
444	/// distinguished from is the entry the terminal will actually paint, not the
445	/// color the theme asked for. Then the nearest entry to `fg` clearing
446	/// [`DISTINCT`] against it wins. When nothing clears it, the entry that gets
447	/// furthest does: at that point the palette cannot honor the design, and the
448	/// most legible approximation beats the closest invisible one.
449	///
450	/// Only for colors whose whole job is to be told apart from their background.
451	/// Applied to every token it would push a deliberately quiet one until it
452	/// shouted.
453	///
454	/// # Panics
455	///
456	/// If `palette` is empty.
457	pub fn quantize_against(fg: Rgb, bg: Rgb, palette: &[Rgb]) -> usize {
458	assert!(!palette.is_empty(), "a palette needs at least one color");
459	let shown = palette[quantize(bg, palette)];
460
461	let mut order: Vec<usize> = (0..palette.len()).collect();
462	order.sort_by(\|a, b\| {
463	oklab_distance(fg, palette[a]).total_cmp(&oklab_distance(fg, palette[b]))
464	});
465
466	order
467	.iter()
468	.copied()
469	.find(\|index\| wcag_contrast(palette[*index], shown) >= DISTINCT)
470	.unwrap_or_else(\|\| {
471	order
472	.iter()
473	.copied()
474	.max_by(\|a, b\| {
475	wcag_contrast(palette[a], shown).total_cmp(&wcag_contrast(palette[b], shown))
476	})
477	.expect("the palette is not empty")
478	})
479	}
480
481	// ============================================================================
482	// Intent resolution
483	// ============================================================================
484
485	/// Authored base intents: (TOML dotted source key, canonical token key).
486	/// These are read straight from the theme; the token key is the CSS-var stem
487	/// (`--{token}`) and the `rgb()` lookup key.
488	pub const BASE_INTENTS: &[(&str, &str)] = &[
489	("surface.page", "surface-page"),
490	("surface.raised", "surface-raised"),
491	("surface.sunken", "surface-sunken"),
492	("surface.overlay", "surface-overlay"),
493	("content.primary", "content"),
494	("content.secondary", "content-secondary"),
495	("content.muted", "content-muted"),
496	("action.primary", "action"),
497	("status.danger", "danger"),
498	("status.success", "success"),
499	("status.warning", "warning"),
500	("status.info", "info"),
501	("line.border", "border"),
502	("category.one", "category-one"),
503	("category.two", "category-two"),
504	("category.three", "category-three"),
505	("category.four", "category-four"),
506	("category.five", "category-five"),
507	("category.six", "category-six"),
508	];
509
510	/// A fully resolved intent layer: every token key → concrete `#rrggbb`.
511	/// Includes both authored base intents and the computed derived intents.
512	#[derive(Debug, Clone, Serialize)]
513	#[serde(rename_all = "camelCase")]
514	pub struct SemanticTokens {
515	pub meta: ThemeMeta,
516	/// token-key → resolved hex. Stable, deterministic ordering.
517	pub intents: BTreeMap<String, String>,
518	}
519
520	impl SemanticTokens {
521	/// Resolved hex for a token key, if present.
522	pub fn hex(&self, key: &str) -> Option<&str> {
523	self.intents.get(key).map(String::as_str)
524	}
525
526	/// Resolved RGB tuple for a token key (for egui / native consumers).
527	pub fn rgb(&self, key: &str) -> Option<(u8, u8, u8)> {
528	self.intents
529	.get(key)
530	.and_then(\|h\| Rgb::from_hex(h))
531	.map(Rgb::tuple)
532	}
533	}
534
535	/// Resolve an authored theme into the full intent token set.
536	///
537	/// 1. Copy each present base intent from the authored colors.
538	/// 2. Compute the derived interactive states from the base intents, using the
539	/// same math the apps used to apply individually (so output is identical).
540	///
541	/// Each derived token is emitted only when its source intents exist, mirroring
542	/// the skip-missing behavior of the rest of the crate.
543	pub fn resolve(theme: &ThemeColors) -> SemanticTokens {
544	let mut intents: BTreeMap<String, String> = BTreeMap::new();
545
546	// 1. Base intents (authored). Copy only values that parse as a hex color and
547	// re-emit them in canonical `#rrggbb` form, so an authored value can never
548	// carry arbitrary bytes into the emitted CSS (the resolved tokens are inlined
549	// raw into a `<style>` block by the web server). A malformed value is skipped,
550	// mirroring the skip-missing behavior for absent intents.
551	for (src, token) in BASE_INTENTS {
552	if let Some(rgb) = theme.colors.get(*src).and_then(\|v\| Rgb::from_hex(v)) {
553	intents.insert((*token).to_string(), rgb.to_hex());
554	}
555	}
556
557	// Helper: parse an already-resolved token to Rgb.
558	let get = \|m: &BTreeMap<String, String>, k: &str\| m.get(k).and_then(\|h\| Rgb::from_hex(h));
559
560	// 2. Derived intents — perceptual (OKLab) steps + WCAG-picked text.
561	// Lightness deltas are in OKLab L units; mix ratios interpolate in OKLab.
562	let mut derived: Vec<(String, Rgb)> = Vec::new();
563	if let Some(action) = get(&intents, "action") {
564	derived.push(("action-hover".into(), lighten(action, 0.05)));
565	derived.push(("content-on-action".into(), readable_on(action)));
566	derived.push(("focus-ring".into(), action));
567	}
568	if let Some(page) = get(&intents, "surface-page") {
569	// Modal scrim: a near-black tone carrying a faint hint of the theme's
570	// hue, at 50% alpha. Anchored very dark (OKLab L=0.08) so it dims the
571	// page on light and dark themes. Emitted as rgba (not a flat hex), so
572	// it is inserted directly rather than through the hex loop below.
573	let mut o = page.to_oklab();
574	o.l = 0.08;
575	let s = Rgb::from_oklab(o);
576	intents.insert(
577	"overlay".into(),
578	format!("rgba({}, {}, {}, 0.5)", s.r, s.g, s.b),
579	);
580	}
581	if let Some(raised) = get(&intents, "surface-raised") {
582	// The two edges of a bevel: a raised control is lit from the top left,
583	// so its top and left edges take `bevel-light` and its bottom and right
584	// edges `bevel-dark`. Inverting the pair gives a pressed state and an
585	// inset well, which is what makes the idiom cheap for a consumer.
586	//
587	// Derived here rather than composed per-app because the two webviews
588	// could do it in `color-mix()` and audiofiles, which is egui, could not.
589	// Geometry (thickness, radius, which side gets which) stays app-side.
590	//
591	// The deltas are asymmetric because the eye is: an equal step down reads
592	// as a smaller change than the same step up, so the shadow is cut deeper
593	// than the highlight is raised.
594	//
595	// A face already at the top of the ramp cannot hold a highlight — the
596	// lightening clamps and the control bevels on two sides without ever
597	// resolving as lit. That is a property of the theme, not of this
598	// derivation; `bevel_edges_are_distinct_from_their_face` names the
599	// shipped themes it currently bites.
600	derived.push(("bevel-light".into(), lighten(raised, 0.14)));
601	derived.push(("bevel-dark".into(), darken(raised, 0.18)));
602
603	// An inset well: the content surface inside a raised container, so a
604	// list reads as content in a container rather than as bands on a panel.
605	// `surface-sunken` cannot serve, because a theme is free to author it
606	// darker than raised (goingson does) and a well has to go the other way.
607	//
608	// Which way is "the other way" depends on the theme, and this is the one
609	// derivation here that inverts. A well is lighter than its face on a
610	// light theme and darker on a dark one, where the bevel pair sidesteps
611	// the question by emitting both directions at once.
612	//
613	// Read the direction off `content` rather than off `Variant`. A theme
614	// whose text is dark is a theme whose surfaces are light, whatever its
615	// `variant` field claims, so this resolves correctly even when that
616	// field is wrong and it keeps the branch on measured color rather than
617	// on metadata.
618	//
619	// Deltas are asymmetric for the same reason the bevel's are, and smaller
620	// than the bevel's because a well is an area rather than an edge. The
621	// step up is the specimen's, measured: #D9DDF4 to #F3F5FD is 0.069.
622	//
623	// A face at the top of its ramp cannot hold a lighter well, the same
624	// clamp `bevel-light` hits; `well_is_visible_against_its_face` names the
625	// shipped themes where it bites.
626	if let Some(content) = get(&intents, "content") {
627	let content_is_darker = content.to_oklab().l < raised.to_oklab().l;
628	let well = if content_is_darker {
629	lighten(raised, 0.07)
630	} else {
631	darken(raised, 0.09)
632	};
633	derived.push(("surface-well".into(), well));
634	}
635	}
636	if let Some(sunken) = get(&intents, "surface-sunken") {
637	derived.push(("hover-surface".into(), sunken));
638	}
639	if let Some(border) = get(&intents, "border") {
640	derived.push(("border-strong".into(), darken(border, 0.05)));
641	}
642
643	for (token, rgb) in derived {
644	intents.insert(token, rgb.to_hex());
645	}
646
647	SemanticTokens {
648	meta: theme.meta.clone(),
649	intents,
650	}
651	}
652
653	/// Emit the resolved intent layer as CSS declarations (no selector), one
654	/// ` --token: #hex;` line each, in deterministic (BTreeMap) order.
655	pub fn intent_css_declarations(tokens: &SemanticTokens) -> String {
656	let mut out = String::new();
657	for (token, hex) in &tokens.intents {
658	out.push_str(" --");
659	out.push_str(token);
660	out.push_str(": ");
661	out.push_str(hex);
662	out.push_str(";\n");
663	}
664	out
665	}
666
667	/// Emit the resolved intent layer as a `:root { … }` block — the single TOML →
668	/// CSS mapping every web surface injects.
669	pub fn intent_css_vars(tokens: &SemanticTokens) -> String {
670	format!(":root {{\n{}}}\n", intent_css_declarations(tokens))
671	}
672
673	// ============================================================================
674	// Loading / parsing
675	// ============================================================================
676
677	/// Validate a theme ID contains only safe characters (alphanumeric, hyphens, underscores).
678	pub fn validate_theme_id(id: &str) -> Result<(), String> {
679	if !id
680	.chars()
681	.all(\|c\| c.is_alphanumeric() \|\| c == '-' \|\| c == '_')
682	{
683	return Err(format!("Invalid theme ID: {id}"));
684	}
685	Ok(())
686	}
687
688	/// Parse the `[meta]` section into `ThemeMeta`.
689	///
690	/// Falls back to the file ID as the name and `"dark"` as the variant.
691	pub fn parse_meta(id: &str, table: &toml::Table, is_custom: bool) -> ThemeMeta {
692	let meta = table.get("meta").and_then(\|m\| m.as_table());
693	let name = meta
694	.and_then(\|m\| m.get("name"))
695	.and_then(\|v\| v.as_str())
696	.unwrap_or(id)
697	.to_string();
698	let variant = meta
699	.and_then(\|m\| m.get("variant"))
700	.and_then(\|v\| v.as_str())
701	.unwrap_or("dark")
702	.to_string();
703
704	ThemeMeta {
705	id: id.to_string(),
706	name,
707	variant,
708	is_custom,
709	}
710	}
711
712	// ============================================================================
713	// Choosing a theme.
714	//
715	// The file half of this crate was always shared; the selection half was not,
716	// and four apps re-rolled it four ways. GoingsOn stores a "system" sentinel in
717	// localStorage, Balanced Breakfast treats an absent value as follow-the-system
718	// and hardcodes two theme ids as its light/dark pair, audiofiles keeps the id
719	// in a synced SQLite table, and the Alloy console parses COLORFGBG. They also
720	// disagreed about what a variant string means: this crate defaults a missing
721	// one to "dark" while alloy_tui parsed an unrecognized one as light.
722	//
723	// What cannot be shared is the store — localStorage, a synced config table and
724	// a TOML file are genuinely different places. What can be shared, and is here,
725	// is the meaning: one vocabulary for variants, one encoding for "what did the
726	// user choose", and one rule for turning that into an id that exists.
727	// ============================================================================
728
729	/// A theme's kind, as declared by `meta.variant`.
730	///
731	/// Three, not two: one shipped theme is `high-contrast`, and an app that
732	/// matched on light-or-dark alone would quietly file it under the wrong one.
733	#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize)]
734	#[serde(rename_all = "kebab-case")]
735	pub enum Variant {
736	Light,
737	Dark,
738	HighContrast,
739	}
740
741	impl Variant {
742	/// The spelling used in a theme file and in [`ThemeMeta::variant`].
743	#[must_use]
744	pub const fn as_str(self) -> &'static str {
745	match self {
746	Variant::Light => "light",
747	Variant::Dark => "dark",
748	Variant::HighContrast => "high-contrast",
749	}
750	}
751
752	/// Read a variant string, or `None` if it names none of them.
753	#[must_use]
754	pub fn parse(raw: &str) -> Option<Self> {
755	match raw {
756	"light" => Some(Variant::Light),
757	"dark" => Some(Variant::Dark),
758	"high-contrast" => Some(Variant::HighContrast),
759	_ => None,
760	}
761	}
762	}
763
764	impl std::fmt::Display for Variant {
765	fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
766	f.write_str(self.as_str())
767	}
768	}
769
770	/// Anything unrecognized reads as dark, which is what [`parse_meta`] already
771	/// does with a missing one. Consumers that guessed light for an unknown string
772	/// were disagreeing with the crate that produced it.
773	impl From<&str> for Variant {
774	fn from(raw: &str) -> Self {
775	Variant::parse(raw).unwrap_or(Variant::Dark)
776	}
777	}
778
779	impl ThemeMeta {
780	/// This theme's variant as a value rather than a string.
781	#[must_use]
782	pub fn kind(&self) -> Variant {
783	Variant::from(self.variant.as_str())
784	}
785	}
786
787	/// The spelling of "follow whatever the system is doing", in every store.
788	pub const FOLLOW: &str = "system";
789
790	/// What the user chose, as opposed to what is being rendered.
791	///
792	/// The distinction is the whole point: `Follow` is a standing instruction that
793	/// resolves differently as the ambient mode changes, and a `Fixed` id is an
794	/// answer that does not. An app that stored only the rendered id could not tell
795	/// the two apart the next time the system flipped to dark.
796	#[derive(Debug, Clone, PartialEq, Eq, Default)]
797	pub enum ThemeSelection {
798	/// Track the ambient light/dark mode.
799	#[default]
800	Follow,
801	/// Always this theme.
802	Fixed(String),
803	}
804
805	impl ThemeSelection {
806	/// Read a stored selection. An empty or absent value is [`Follow`], which
807	/// is what an app with nothing saved yet should do.
808	///
809	/// [`Follow`]: ThemeSelection::Follow
810	#[must_use]
811	pub fn parse(raw: Option<&str>) -> Self {
812	match raw.map(str::trim) {
813	None \| Some("" \| FOLLOW) => ThemeSelection::Follow,
814	Some(id) => ThemeSelection::Fixed(id.to_string()),
815	}
816	}
817
818	/// The string to persist, whatever the store is.
819	#[must_use]
820	pub fn as_str(&self) -> &str {
821	match self {
822	ThemeSelection::Follow => FOLLOW,
823	ThemeSelection::Fixed(id) => id,
824	}
825	}
826
827	/// Turn a selection into a theme id that exists.
828	///
829	/// `ambient` is the light/dark mode the app learned however it can: a
830	/// `prefers-color-scheme` media query, an OS appearance API, `COLORFGBG`
831	/// from a terminal. `available` is what [`list_themes_from_dirs`] found.
832	///
833	/// A `Fixed` id that is no longer on disk falls through to the same path as
834	/// `Follow` rather than being returned anyway. Themes are deletable in
835	/// three of the four apps, and handing back an id that will fail to load
836	/// only moves the error somewhere less helpful.
837	///
838	/// The fallback chain is: the app's own default for the ambient mode if it
839	/// is installed, then any installed theme of that variant, then the app's
840	/// default regardless. The last step means this always returns something,
841	/// and an app with no theme directory at all gets the id it ships with and
842	/// the load error it would have had anyway.
843	#[must_use]
844	pub fn resolve(
845	&self,
846	ambient: Variant,
847	defaults: &ThemeDefaults,
848	available: &[ThemeMeta],
849	) -> String {
850	let installed = \|id: &str\| available.iter().any(\|meta\| meta.id == id);
851
852	if let ThemeSelection::Fixed(id) = self
853	&& installed(id)
854	{
855	return id.clone();
856	}
857
858	let preferred = defaults.for_variant(ambient);
859	if installed(preferred) {
860	return preferred.to_string();
861	}
862	available
863	.iter()
864	.find(\|meta\| meta.kind() == ambient)
865	.map_or_else(\|\| preferred.to_string(), \|meta\| meta.id.clone())
866	}
867	}
868
869	impl std::fmt::Display for ThemeSelection {
870	fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
871	f.write_str(self.as_str())
872	}
873	}
874
875	/// The themes an app falls back to, one per ambient mode.
876	///
877	/// App-specific on purpose: which theme is "the app's own" is the app's
878	/// identity, not this crate's business. What is shared is everything around it.
879	#[derive(Debug, Clone)]
880	pub struct ThemeDefaults {
881	light: String,
882	dark: String,
883	high_contrast: Option<String>,
884	}
885
886	impl ThemeDefaults {
887	pub fn new(light: impl Into<String>, dark: impl Into<String>) -> Self {
888	Self {
889	light: light.into(),
890	dark: dark.into(),
891	high_contrast: None,
892	}
893	}
894
895	/// Name a theme for a high-contrast ambient mode. Without one, that mode
896	/// falls back to the dark default, which is the safer of the two to read.
897	#[must_use]
898	pub fn high_contrast(mut self, id: impl Into<String>) -> Self {
899	self.high_contrast = Some(id.into());
900	self
901	}
902
903	#[must_use]
904	pub fn for_variant(&self, variant: Variant) -> &str {
905	match variant {
906	Variant::Light => &self.light,
907	Variant::Dark => &self.dark,
908	Variant::HighContrast => self.high_contrast.as_ref().unwrap_or(&self.dark),
909	}
910	}
911	}
912
913	// ============================================================================
914	// Where themes are looked for.
915	//
916	// Four apps built this vector by hand, two of them byte-for-byte identically,
917	// and one of them built it backwards: the Alloy console pushed the user's own
918	// directory first, under a comment saying "highest precedence first", when both
919	// consumers of the vector resolve last wins. A user's custom theme lost to
920	// the packaged one of the same id.
921	//
922	// Hence a builder that names the tiers rather than a function taking a vector.
923	// The precedence is stated once, here, and a caller cannot express it backwards
924	// because the order is not theirs to choose.
925	// ============================================================================
926
927	/// Builds the search path [`load_theme`] and [`list_themes_from_dirs`] take.
928	///
929	/// Tiers are added in whatever order is convenient and always end up in
930	/// precedence order: the user's own themes win, then whatever the system
931	/// ships, then whatever the app bundles.
932	///
933	/// A directory that does not exist is dropped rather than carried, so callers
934	/// can offer every tier they might have without checking each one.
935	#[derive(Debug, Default, Clone)]
936	pub struct ThemeDirs {
937	bundled: Vec<PathBuf>,
938	system: Vec<PathBuf>,
939	custom: Option<PathBuf>,
940	}
941
942	impl ThemeDirs {
943	#[must_use]
944	pub fn new() -> Self {
945	Self::default()
946	}
947
948	/// Themes the app ships with. Lowest precedence.
949	///
950	/// Takes more than one because a Tauri app has two: the bundled resource
951	/// directory in production, and the tree `build.rs` materialized for a
952	/// `cargo run` that has no resource directory at all.
953	#[must_use]
954	pub fn bundled(mut self, dir: Option<PathBuf>) -> Self {
955	self.bundled.extend(dir);
956	self
957	}
958
959	/// Themes the machine ships, from an image or a package. Overrides bundled.
960	#[must_use]
961	pub fn system(mut self, dir: Option<PathBuf>) -> Self {
962	self.system.extend(dir);
963	self
964	}
965
966	/// The user's own themes. Highest precedence, and the only tier flagged
967	/// custom, which is what makes them exportable and deletable.
968	#[must_use]
969	pub fn custom(mut self, dir: Option<PathBuf>) -> Self {
970	self.custom = dir;
971	self
972	}
973
974	/// The search path, lowest precedence first.
975	#[must_use]
976	pub fn build(self) -> Vec<(PathBuf, bool)> {
977	let mut dirs = Vec::new();
978	for dir in self.bundled.into_iter().chain(self.system) {
979	if dir.is_dir() {
980	dirs.push((dir, false));
981	}
982	}
983	if let Some(dir) = self.custom
984	&& dir.is_dir()
985	{
986	dirs.push((dir, true));
987	}
988	dirs
989	}
990	}
991
992	/// Extract the intent color sections into a flat `HashMap` with dotted keys
993	/// like `"surface.page"`, `"status.danger"`, `"category.one"`.
994	pub fn extract_colors(table: &toml::Table) -> HashMap<String, String> {
995	let mut colors = HashMap::new();
996	for section in COLOR_SECTIONS {
997	if let Some(sect) = table.get(*section).and_then(\|s\| s.as_table()) {
998	for (key, val) in sect {
999	if let Some(color) = val.as_str() {
1000	colors.insert(format!("{section}.{key}"), color.to_string());
1001	}
1002	}
1003	}
1004	}
1005	colors
1006	}
1007
1008	/// Scan directories for `.toml` theme files and return metadata for each.
1009	///
1010	/// Directories are checked in order; later entries override earlier ones by ID.
1011	/// Each entry in `dirs` is `(path, is_custom)`.
1012	pub fn list_themes_from_dirs(dirs: &[(PathBuf, bool)]) -> Vec<ThemeMeta> {
1013	let mut seen: HashMap<String, ThemeMeta> = HashMap::new();
1014
1015	for (dir, is_custom) in dirs {
1016	let Ok(entries) = std::fs::read_dir(dir) else {
1017	continue;
1018	};
1019
1020	for entry in entries {
1021	let Ok(entry) = entry else {
1022	continue;
1023	};
1024	let path = entry.path();
1025	if path.extension().and_then(\|e\| e.to_str()) != Some("toml") {
1026	continue;
1027	}
1028
1029	let id = path
1030	.file_stem()
1031	.and_then(\|s\| s.to_str())
1032	.unwrap_or_default()
1033	.to_string();
1034
1035	let Ok(content) = std::fs::read_to_string(&path) else {
1036	continue;
1037	};
1038	let table: toml::Table = match content.parse() {
1039	Ok(t) => t,
1040	Err(_) => continue,
1041	};
1042
1043	seen.insert(id.clone(), parse_meta(&id, &table, *is_custom));
1044	}
1045	}
1046
1047	let mut themes: Vec<ThemeMeta> = seen.into_values().collect();
1048	themes.sort_by(\|a, b\| a.name.cmp(&b.name));
1049	themes
1050	}
1051
1052	/// Find a theme file by ID in the given directories.
1053	///
1054	/// Checks directories in reverse order so the highest-priority directory wins.
1055	/// Returns `(path, is_custom)` or `None` if not found.
1056	pub fn find_theme_path(dirs: &[(PathBuf, bool)], id: &str) -> Option<(PathBuf, bool)> {
1057	let filename = format!("{id}.toml");
1058
1059	for (dir, is_custom) in dirs.iter().rev() {
1060	let path = dir.join(&filename);
1061	if path.is_file() {
1062	return Some((path, *is_custom));
1063	}
1064	}
1065
1066	None
1067	}
1068
1069	/// Parse a complete theme (metadata + colors) from raw TOML content, with no
1070	/// filesystem access. For callers that embed themes at compile time.
1071	pub fn parse_theme_str(id: &str, content: &str, is_custom: bool) -> Result<ThemeColors, String> {
1072	validate_theme_id(id)?;
1073	let table: toml::Table = content
1074	.parse()
1075	.map_err(\|e\| format!("Failed to parse theme '{id}': {e}"))?;
1076	let meta = parse_meta(id, &table, is_custom);
1077	let colors = extract_colors(&table);
1078	Ok(ThemeColors { meta, colors })
1079	}
1080
1081	/// Load a complete theme (metadata + colors) by ID from the given directories.
1082	pub fn load_theme(dirs: &[(PathBuf, bool)], id: &str) -> Result<ThemeColors, String> {
1083	validate_theme_id(id)?;
1084
1085	let (path, is_custom) =
1086	find_theme_path(dirs, id).ok_or_else(\|\| format!("Theme '{id}' not found"))?;
1087
1088	let content = std::fs::read_to_string(&path)
1089	.map_err(\|e\| format!("Failed to read {}: {}", path.display(), e))?;
1090
1091	let table: toml::Table = content
1092	.parse()
1093	.map_err(\|e\| format!("Failed to parse {}: {}", path.display(), e))?;
1094
1095	let meta = parse_meta(id, &table, is_custom);
1096	let colors = extract_colors(&table);
1097
1098	Ok(ThemeColors { meta, colors })
1099	}
1100
1101	/// Load a theme and resolve it to the full intent token set in one step.
1102	pub fn load_semantic(dirs: &[(PathBuf, bool)], id: &str) -> Result<SemanticTokens, String> {
1103	Ok(resolve(&load_theme(dirs, id)?))
1104	}
1105
1106	/// Import a theme TOML file into the custom themes directory.
1107	///
1108	/// Validates that the file is parseable TOML with at least one intent color
1109	/// section, then copies it to `custom_dir/{id}.toml`. Returns the theme metadata.
1110	pub fn import_theme(source_path: &Path, custom_dir: &Path) -> Result<ThemeMeta, String> {
1111	let content = std::fs::read_to_string(source_path)
1112	.map_err(\|e\| format!("Failed to read {}: {}", source_path.display(), e))?;
1113
1114	let table: toml::Table = content.parse().map_err(\|e\| format!("Invalid TOML: {e}"))?;
1115
1116	let has_colors = COLOR_SECTIONS
1117	.iter()
1118	.any(\|s\| table.get(*s).and_then(\|v\| v.as_table()).is_some());
1119	if !has_colors {
1120	return Err(format!(
1121	"Theme file must have at least one color section ({})",
1122	COLOR_SECTIONS.join(", ")
1123	));
1124	}
1125
1126	let id = source_path
1127	.file_stem()
1128	.and_then(\|s\| s.to_str())
1129	.ok_or("Invalid file name")?
1130	.to_string();
1131	validate_theme_id(&id)?;
1132
1133	std::fs::create_dir_all(custom_dir)
1134	.map_err(\|e\| format!("Failed to create {}: {}", custom_dir.display(), e))?;
1135
1136	let dest = custom_dir.join(format!("{id}.toml"));
1137	std::fs::copy(source_path, &dest).map_err(\|e\| format!("Failed to copy theme: {e}"))?;
1138
1139	Ok(parse_meta(&id, &table, true))
1140	}
1141
1142	/// Delete a custom theme by ID.
1143	///
1144	/// Only operates on `custom_dir` — bundled themes are not deletable through
1145	/// this entry point.
1146	pub fn delete_theme(custom_dir: &Path, id: &str) -> Result<(), String> {
1147	validate_theme_id(id)?;
1148
1149	let path = custom_dir.join(format!("{id}.toml"));
1150	if !path.is_file() {
1151	return Err(format!("Custom theme '{id}' not found"));
1152	}
1153
1154	std::fs::remove_file(&path).map_err(\|e\| format!("Failed to delete {}: {}", path.display(), e))
1155	}
1156
1157	/// A four-color preview for theme thumbnails: the representative swatch from
1158	/// each of the principal roles.
1159	#[derive(Debug, Clone, Serialize)]
1160	#[serde(rename_all = "camelCase")]
1161	pub struct ThemePreview {
1162	pub meta: ThemeMeta,
1163	/// Page background (`surface.page`).
1164	pub background: Option<String>,
1165	/// Body text (`content.primary`).
1166	pub foreground: Option<String>,
1167	/// Brand/interactive color (`action.primary`).
1168	pub accent: Option<String>,
1169	/// Divider/outline color (`line.border`).
1170	pub border: Option<String>,
1171	}
1172
1173	fn color_at(table: &toml::Table, section: &str, key: &str) -> Option<String> {
1174	table
1175	.get(section)
1176	.and_then(\|s\| s.as_table())
1177	.and_then(\|s\| s.get(key))
1178	.and_then(\|v\| v.as_str())
1179	.map(std::string::ToString::to_string)
1180	}
1181
1182	/// Load just the preview swatches for a theme — for UI thumbnails.
1183	pub fn load_theme_preview(dirs: &[(PathBuf, bool)], id: &str) -> Result<ThemePreview, String> {
1184	validate_theme_id(id)?;
1185
1186	let (path, is_custom) =
1187	find_theme_path(dirs, id).ok_or_else(\|\| format!("Theme '{id}' not found"))?;
1188
1189	let content = std::fs::read_to_string(&path)
1190	.map_err(\|e\| format!("Failed to read {}: {}", path.display(), e))?;
1191
1192	let table: toml::Table = content
1193	.parse()
1194	.map_err(\|e\| format!("Failed to parse {}: {}", path.display(), e))?;
1195
1196	Ok(ThemePreview {
1197	meta: parse_meta(id, &table, is_custom),
1198	background: color_at(&table, "surface", "page"),
1199	foreground: color_at(&table, "content", "primary"),
1200	accent: color_at(&table, "action", "primary"),
1201	border: color_at(&table, "line", "border"),
1202	})
1203	}
1204
1205	/// Export a theme to a user-chosen path.
1206	pub fn export_theme(dirs: &[(PathBuf, bool)], id: &str, dest_path: &Path) -> Result<(), String> {
1207	validate_theme_id(id)?;
1208
1209	let (source, _) = find_theme_path(dirs, id).ok_or_else(\|\| format!("Theme '{id}' not found"))?;
1210
1211	std::fs::copy(&source, dest_path).map_err(\|e\| format!("Failed to export theme: {e}"))?;
1212
1213	Ok(())
1214	}
1215
1216	/// The themes this crate ships, embedded at compile time.
1217	///
1218	/// `include_dir` is an implementation detail: the public API hands back plain
1219	/// `(id, toml_source)` pairs, so how the data is embedded can change without
1220	/// a breaking release.
1221	static EMBEDDED: include_dir::Dir<'static> =
1222	include_dir::include_dir!("$CARGO_MANIFEST_DIR/themes");
1223
1224	/// The themes this crate ships, as `(id, toml_source)` pairs.
1225	///
1226	/// This is the path-free way to reach the bundled set, for consumers that
1227	/// cannot rely on a directory existing at runtime: a crate pulled from
1228	/// crates.io lives in a registry checkout whose location is not knowable at
1229	/// compile time, so `include_dir!` and asset-bundling globs in the depending
1230	/// crate have nothing stable to point at. Embedding here and re-exporting the
1231	/// contents gives them one source of truth without a path.
1232	///
1233	/// Ordering follows the embedded directory and is not guaranteed; collect and
1234	/// sort by id where a stable order matters (a theme picker, say).
1235	pub fn embedded_themes() -> impl Iterator<Item = (&'static str, &'static str)> {
1236	EMBEDDED.files().filter_map(\|file\| {
1237	let path = file.path();
1238	if path.extension().and_then(\|e\| e.to_str()) != Some("toml") {
1239	return None;
1240	}
1241	let id = path.file_stem()?.to_str()?;
1242	Some((id, file.contents_utf8()?))
1243	})
1244	}
1245
1246	/// The theme directory this crate ships, for use as a build-from-source
1247	/// fallback.
1248	///
1249	/// Resolves against `makeover`'s own manifest directory, fixed at compile
1250	/// time, so it works from a path dependency and from a cargo git checkout
1251	/// alike. Installed systems should put their packaged theme directory ahead
1252	/// of this in the search path; this is the entry that keeps `cargo run` in a
1253	/// fresh clone from coming up with no themes at all.
1254	///
1255	/// Returns `None` when the directory is absent — a cargo cache that has been
1256	/// cleaned, or a vendored copy that dropped the data — so callers degrade to
1257	/// their remaining search path rather than failing.
1258	pub fn bundled_themes_dir() -> Option<PathBuf> {
1259	let themes = Path::new(env!("CARGO_MANIFEST_DIR")).join("themes");
1260	if themes.is_dir() { Some(themes) } else { None }
1261	}
1262
1263	#[cfg(test)]
1264	mod tests {
1265	use super::*;
1266	use std::fs;
1267
1268	// ---- id validation ----
1269
1270	#[test]
1271	fn validate_theme_id_alphanumeric() {
1272	assert!(validate_theme_id("darkmode").is_ok());
1273	assert!(validate_theme_id("Theme123").is_ok());
1274	}
1275
1276	#[test]
1277	fn validate_theme_id_hyphens_underscores() {
1278	assert!(validate_theme_id("dark-mode").is_ok());
1279	assert!(validate_theme_id("my_theme_v2").is_ok());
1280	}
1281
1282	#[test]
1283	fn validate_theme_id_rejects_path_traversal() {
1284	assert!(validate_theme_id("../etc/passwd").is_err());
1285	assert!(validate_theme_id("foo/bar").is_err());
1286	assert!(validate_theme_id("theme.toml").is_err());
1287	}
1288
1289	// ---- low-color terminals ----
1290
1291	#[test]
1292	fn the_ansi_palette_is_sixteen_distinct_colors() {
1293	let mut seen: Vec<(u8, u8, u8)> = ANSI_16.iter().map(\|c\| c.tuple()).collect();
1294	seen.sort_unstable();
1295	seen.dedup();
1296	assert_eq!(seen.len(), 16);
1297	}
1298
1299	#[test]
1300	fn quantize_picks_the_obvious_entry() {
1301	let black = Rgb { r: 0, g: 0, b: 0 };
1302	let white = Rgb {
1303	r: 255,
1304	g: 255,
1305	b: 255,
1306	};
1307	assert_eq!(quantize(black, &ANSI_16), 0);
1308	assert_eq!(quantize(white, &ANSI_16), 15);
1309	}
1310
1311	// Nearest-entry quantization is per-color, so two colors a theme keeps
1312	// apart can arrive as one. These two are both closest to the palette's
1313	// light gray, and a border drawn in one on a page painted the other is not
1314	// drawn at all.
1315	#[test]
1316	fn two_colors_can_quantize_to_one_entry() {
1317	let page = Rgb::from_hex("#a8a8a8").unwrap();
1318	let border = Rgb::from_hex("#b4b4b4").unwrap();
1319
1320	assert_eq!(quantize(page, &ANSI_16), quantize(border, &ANSI_16));
1321	assert!(quantize_against(border, page, &ANSI_16) != quantize(page, &ANSI_16));
1322	}
1323
1324	#[test]
1325	fn quantize_against_keeps_the_border_off_the_page() {
1326	let page = Rgb::from_hex("#e4ded6").unwrap();
1327	let border = Rgb::from_hex("#7f786d").unwrap();
1328
1329	let shown_page = ANSI_16[quantize(page, &ANSI_16)];
1330	let shown_border = ANSI_16[quantize_against(border, page, &ANSI_16)];
1331
1332	assert!(
1333	wcag_contrast(shown_border, shown_page) >= DISTINCT,
1334	"border {} on page {} is {:.2}:1",
1335	shown_border.to_hex(),
1336	shown_page.to_hex(),
1337	wcag_contrast(shown_border, shown_page)
1338	);
1339	}
1340
1341	// A color that already reads against its background is left where it is,
1342	// so this can be applied without redesigning what already worked.
1343	#[test]
1344	fn quantize_against_leaves_a_readable_color_alone() {
1345	let page = Rgb::from_hex("#e4ded6").unwrap();
1346	let text = Rgb::from_hex("#1a1816").unwrap();
1347
1348	assert_eq!(
1349	quantize_against(text, page, &ANSI_16),
1350	quantize(text, &ANSI_16)
1351	);
1352	}
1353
1354	// With nothing in the palette to satisfy the request, the most legible
1355	// entry is the answer. Returning the nearest one would return the
1356	// background itself, which is the failure this function exists to avoid.
1357	#[test]
1358	fn an_impossible_palette_gets_the_most_legible_entry() {
1359	let page = Rgb::from_hex("#ffffff").unwrap();
1360	let border = Rgb::from_hex("#fefefe").unwrap();
1361	let palette = [
1362	Rgb::from_hex("#ffffff").unwrap(),
1363	Rgb::from_hex("#fdfdfd").unwrap(),
1364	];
1365
1366	let chosen = palette[quantize_against(border, page, &palette)];
1367	assert_eq!(chosen.to_hex(), "#fdfdfd");
1368	}
1369
1370	// ---- meta ----
1371
1372	#[test]
1373	fn parse_meta_with_name_and_variant() {
1374	let table: toml::Table = "[meta]\nname = \"Nord\"\nvariant = \"light\"\n"
1375	.parse()
1376	.unwrap();
1377	let meta = parse_meta("nord", &table, false);
1378	assert_eq!(meta.id, "nord");
1379	assert_eq!(meta.name, "Nord");
1380	assert_eq!(meta.variant, "light");
1381	assert!(!meta.is_custom);
1382	}
1383
1384	#[test]
1385	fn parse_meta_defaults_to_id_and_dark() {
1386	let table: toml::Table = "".parse().unwrap();
1387	let meta = parse_meta("fallback", &table, true);
1388	assert_eq!(meta.name, "fallback");
1389	assert_eq!(meta.variant, "dark");
1390	assert!(meta.is_custom);
1391	}
1392
1393	// ---- color math (formulas must match the apps they came from) ----
1394
1395	#[test]
1396	fn rgb_hex_roundtrip() {
1397	assert_eq!(
1398	Rgb::from_hex("#6196FF").unwrap(),
1399	Rgb {
1400	r: 0x61,
1401	g: 0x96,
1402	b: 0xff
1403	}
1404	);
1405	assert_eq!(
1406	Rgb::from_hex("#abc").unwrap(),
1407	Rgb {
1408	r: 0xaa,
1409	g: 0xbb,
1410	b: 0xcc
1411	}
1412	);
1413	assert_eq!(
1414	Rgb {
1415	r: 0x61,
1416	g: 0x96,
1417	b: 0xff
1418	}
1419	.to_hex(),
1420	"#6196ff"
1421	);
1422	assert!(Rgb::from_hex("not-a-color").is_none());
1423	}
1424
1425	#[test]
1426	fn oklab_roundtrips_within_tolerance() {
1427	for hex in ["#6196ff", "#2e3440", "#ffffff", "#000000", "#c0392b"] {
1428	let c = Rgb::from_hex(hex).unwrap();
1429	let back = Rgb::from_oklab(c.to_oklab());
1430	// Gamut round-trip is near-exact (±1 per channel from rounding).
1431	assert!((c.r as i16 - back.r as i16).abs() <= 1, "{hex} r");
1432	assert!((c.g as i16 - back.g as i16).abs() <= 1, "{hex} g");
1433	assert!((c.b as i16 - back.b as i16).abs() <= 1, "{hex} b");
1434	}
1435	}
1436
1437	#[test]
1438	fn wcag_contrast_known_pairs() {
1439	let white = Rgb {
1440	r: 255,
1441	g: 255,
1442	b: 255,
1443	};
1444	let black = Rgb { r: 0, g: 0, b: 0 };
1445	assert!((wcag_contrast(white, black) - 21.0).abs() < 0.01);
1446	assert!((wcag_contrast(white, white) - 1.0).abs() < 0.01);
1447	}
1448
1449	#[test]
1450	fn readable_on_picks_by_wcag() {
1451	assert_eq!(
1452	readable_on(Rgb {
1453	r: 255,
1454	g: 255,
1455	b: 255
1456	}),
1457	Rgb { r: 0, g: 0, b: 0 }
1458	);
1459	assert_eq!(
1460	readable_on(Rgb { r: 0, g: 0, b: 0 }),
1461	Rgb {
1462	r: 255,
1463	g: 255,
1464	b: 255
1465	}
1466	);
1467	// A light blue action -> black text reads better.
1468	let action = Rgb::from_hex("#6196ff").unwrap();
1469	assert_eq!(readable_on(action), Rgb { r: 0, g: 0, b: 0 });
1470	}
1471
1472	#[test]
1473	fn lighten_darken_move_oklab_lightness() {
1474	let c = Rgb::from_hex("#6196ff").unwrap();
1475	let l0 = c.to_oklab().l;
1476	assert!(lighten(c, 0.05).to_oklab().l > l0);
1477	assert!(darken(c, 0.05).to_oklab().l < l0);
1478	}
1479
1480	#[test]
1481	fn mix_endpoints_and_midpoint() {
1482	let a = Rgb::from_hex("#000000").unwrap();
1483	let b = Rgb::from_hex("#6196ff").unwrap();
1484	assert_eq!(mix(a, b, 0.0), a);
1485	assert_eq!(mix(a, b, 1.0), b);
1486	// Midpoint sits between the endpoints in OKLab lightness.
1487	let mid = mix(a, b, 0.5).to_oklab().l;
1488	assert!(mid > a.to_oklab().l && mid < b.to_oklab().l);
1489	}
1490
1491	// ---- extract + resolve ----
1492
1493	fn nord_toml() -> &'static str {
1494	r##"
1495	[meta]
1496	name = "Nord"
1497	variant = "dark"
1498
1499	[surface]
1500	page = "#2e3440"
1501	raised = "#3b4252"
1502	sunken = "#434c5e"
1503	overlay = "#3b4252"
1504
1505	[content]
1506	primary = "#d8dee9"
1507	secondary = "#e5e9f0"
1508	muted = "#616e88"
1509
1510	[action]
1511	primary = "#81a1c1"
1512
1513	[status]
1514	danger = "#bf616a"
1515	success = "#a3be8c"
1516	warning = "#ebcb8b"
1517	info = "#88c0d0"
1518
1519	[line]
1520	border = "#4c566a"
1521
1522	[category]
1523	one = "#bf616a"
1524	two = "#a3be8c"
1525	three = "#81a1c1"
1526	four = "#ebcb8b"
1527	five = "#b48ead"
1528	six = "#88c0d0"
1529	"##
1530	}
1531
1532	#[test]
1533	fn extract_colors_reads_intent_sections() {
1534	let table: toml::Table = nord_toml().parse().unwrap();
1535	let colors = extract_colors(&table);
1536	assert_eq!(colors.get("surface.page").unwrap(), "#2e3440");
1537	assert_eq!(colors.get("content.primary").unwrap(), "#d8dee9");
1538	assert_eq!(colors.get("action.primary").unwrap(), "#81a1c1");
1539	assert_eq!(colors.get("status.danger").unwrap(), "#bf616a");
1540	assert_eq!(colors.get("line.border").unwrap(), "#4c566a");
1541	assert_eq!(colors.get("category.five").unwrap(), "#b48ead");
1542	assert_eq!(colors.len(), 19);
1543	}
1544
1545	#[test]
1546	fn resolve_base_intents_passthrough() {
1547	let theme = parse_theme_str("nord", nord_toml(), false).unwrap();
1548	let t = resolve(&theme);
1549	assert_eq!(t.hex("surface-page"), Some("#2e3440"));
1550	assert_eq!(t.hex("content"), Some("#d8dee9")); // content.primary -> content
1551	assert_eq!(t.hex("content-muted"), Some("#616e88"));
1552	assert_eq!(t.hex("action"), Some("#81a1c1"));
1553	assert_eq!(t.hex("danger"), Some("#bf616a"));
1554	assert_eq!(t.hex("border"), Some("#4c566a"));
1555	assert_eq!(t.hex("category-five"), Some("#b48ead"));
1556	}
1557
1558	#[test]
1559	fn resolve_derived_intents() {
1560	let theme = parse_theme_str("nord", nord_toml(), false).unwrap();
1561	let t = resolve(&theme);
1562	let action = Rgb::from_hex("#81a1c1").unwrap();
1563	let page = Rgb::from_hex("#2e3440").unwrap();
1564	let _ = page;
1565	assert_eq!(
1566	t.hex("action-hover").unwrap(),
1567	lighten(action, 0.05).to_hex()
1568	);
1569	assert_eq!(
1570	t.hex("content-on-action").unwrap(),
1571	readable_on(action).to_hex()
1572	);
1573	assert_eq!(t.hex("focus-ring"), Some("#81a1c1"));
1574	assert_eq!(t.hex("hover-surface"), Some("#434c5e")); // = surface.sunken
1575	// Pruned by the usage audit (0 consumers): action-active, the *-surface
1576	// tints, selection, row-stripe. Apps that need them derive inline via
1577	// the shared mix().
1578	assert!(t.hex("action-active").is_none());
1579	assert!(t.hex("danger-surface").is_none());
1580	assert!(t.hex("selection").is_none());
1581	assert!(t.hex("row-stripe").is_none());
1582	}
1583
1584	#[test]
1585	fn resolve_bevel_intents() {
1586	let theme = parse_theme_str("nord", nord_toml(), false).unwrap();
1587	let t = resolve(&theme);
1588	let raised = Rgb::from_hex("#3b4252").unwrap();
1589	assert_eq!(
1590	t.hex("bevel-light").unwrap(),
1591	lighten(raised, 0.14).to_hex()
1592	);
1593	assert_eq!(t.hex("bevel-dark").unwrap(), darken(raised, 0.18).to_hex());
1594	}
1595
1596	// A bevel is two edges around one face, so both edges have to be visibly off
1597	// that face or the control never resolves as lit. The lightening clamps at
1598	// the top of the ramp, which means a theme authoring a white raised surface
1599	// gets a highlight identical to the surface it is meant to sit on.
1600	//
1601	// The list is asserted rather than merely reported so that changing a theme
1602	// has to come here and say so. Shrinking it is the fix; growing it is a
1603	// regression in the theme, not in this derivation.
1604	#[test]
1605	fn bevel_edges_are_distinct_from_their_face() {
1606	const CANNOT_BEVEL: &[&str] = &["neobrute", "oxocarbon-light"];
1607
1608	let mut degenerate: Vec<String> = Vec::new();
1609	for (id, source) in embedded_themes() {
1610	let theme = parse_theme_str(id, source, false).unwrap();
1611	let t = resolve(&theme);
1612	let Some(raised) = t.hex("surface-raised") else {
1613	continue;
1614	};
1615	let light = t.hex("bevel-light").expect("raised implies bevel-light");
1616	let dark = t.hex("bevel-dark").expect("raised implies bevel-dark");
1617	if light == raised \|\| dark == raised {
1618	degenerate.push(id.to_string());
1619	}
1620	}
1621	degenerate.sort();
1622
1623	assert_eq!(
1624	degenerate, CANNOT_BEVEL,
1625	"themes whose raised surface cannot hold both bevel edges"
1626	);
1627	}
1628
1629	// The well inverts by theme, so assert both directions explicitly rather
1630	// than only the one the light themes happen to take.
1631	#[test]
1632	fn resolve_well_intent_follows_the_content_direction() {
1633	// nord is dark: light text on a dark raised surface, so the well goes
1634	// down and away from the text.
1635	let dark = resolve(&parse_theme_str("nord", nord_toml(), false).unwrap());
1636	let dark_raised = Rgb::from_hex("#3b4252").unwrap();
1637	assert_eq!(
1638	dark.hex("surface-well").unwrap(),
1639	darken(dark_raised, 0.09).to_hex()
1640	);
1641
1642	// The shipped light themes take the other branch.
1643	let goingson = embedded_themes()
1644	.into_iter()
1645	.find(\|(id, _)\| *id == "goingson")
1646	.expect("goingson is embedded")
1647	.1;
1648	let light = resolve(&parse_theme_str("goingson", goingson, false).unwrap());
1649	let light_raised = light
1650	.hex("surface-raised")
1651	.and_then(Rgb::from_hex)
1652	.expect("goingson authors a raised surface");
1653	assert_eq!(
1654	light.hex("surface-well").unwrap(),
1655	lighten(light_raised, 0.07).to_hex()
1656	);
1657	}
1658
1659	// A well is a fill, not an edge, so the only thing that makes it read is
1660	// being a different color from the surface it is cut into.
1661	//
1662	// Same shape and the same asserted-list discipline as
1663	// `bevel_edges_are_distinct_from_their_face`, and it bites the same two
1664	// themes for the same reason: a raised surface already at the top of the
1665	// ramp has nothing lighter to go to.
1666	#[test]
1667	fn well_is_distinct_from_its_face() {
1668	const CANNOT_WELL: &[&str] = &["neobrute", "oxocarbon-light"];
1669
1670	let mut degenerate: Vec<String> = Vec::new();
1671	for (id, source) in embedded_themes() {
1672	let theme = parse_theme_str(id, source, false).unwrap();
1673	let t = resolve(&theme);
1674	let Some(raised) = t.hex("surface-raised") else {
1675	continue;
1676	};
1677	let well = t.hex("surface-well").expect("raised implies surface-well");
1678	if well == raised {
1679	degenerate.push(id.to_string());
1680	}
1681	}
1682	degenerate.sort();
1683
1684	assert_eq!(
1685	degenerate, CANNOT_WELL,
1686	"themes whose raised surface cannot hold a well"
1687	);
1688	}
1689
1690	// Distinct is not the same as visible. A face near the top of the ramp
1691	// clamps partway rather than exactly, which yields a well that differs from
1692	// its face by a hex digit and by nothing the eye can find. `rosepine-dawn`
1693	// authors raised at L=0.987 and gets 0.009 of the 0.07 it asked for.
1694	//
1695	// Worth a separate test from the one above because the fix differs: an
1696	// exactly-degenerate theme needs its raised surface off the ramp end, while
1697	// these need it merely lowered. Both fixes are the theme's, not this
1698	// derivation's, which is why the list is asserted rather than warned about.
1699	#[test]
1700	fn well_is_visible_against_its_face() {
1701	// Below this, the well and its face are the same surface to a reader.
1702	const MIN_DELTA_L: f32 = 0.02;
1703	const CANNOT_HOLD_A_VISIBLE_WELL: &[&str] =
1704	&["neobrute", "oxocarbon-light", "rosepine-dawn"];
1705
1706	let mut invisible: Vec<String> = Vec::new();
1707	for (id, source) in embedded_themes() {
1708	let theme = parse_theme_str(id, source, false).unwrap();
1709	let t = resolve(&theme);
1710	let (Some(raised), Some(well)) = (
1711	t.hex("surface-raised").and_then(Rgb::from_hex),
1712	t.hex("surface-well").and_then(Rgb::from_hex),
1713	) else {
1714	continue;
1715	};
1716	if (well.to_oklab().l - raised.to_oklab().l).abs() < MIN_DELTA_L {
1717	invisible.push(id.to_string());
1718	}
1719	}
1720	invisible.sort();
1721
1722	assert_eq!(
1723	invisible, CANNOT_HOLD_A_VISIBLE_WELL,
1724	"themes whose well is too close to its face to read as one"
1725	);
1726	}
1727
1728	// What the bevel pair does on a sixteen-color terminal, measured across the
1729	// shipped set rather than assumed. Two results, both load-bearing for a
1730	// consumer that has to render one there.
1731	//
1732	// Exactly one edge survives, never both. A raised face quantizes onto one of
1733	// the palette's three grays, and the palette is too coarse to hold anything
1734	// between that entry and its neighbour, so whichever edge is pushed toward
1735	// the end of the ramp the face already sits on lands back on the face. Light
1736	// themes and most dark ones keep the shadow and lose the highlight; a face
1737	// that quantizes to black keeps the highlight and loses the shadow.
1738	//
1739	// So a low-color consumer draws the single edge it can render, on the side
1740	// the palette left it, rather than a bevel that resolves on two sides.
1741	//
1742	// And `quantize_against` is the wrong function for this pair, though it is
1743	// the right one for a border. It answers "nearest entry that clears DISTINCT
1744	// against the background", which has no notion of direction, so both edges
1745	// are pushed onto the same contrasting entry and the bevel inverts on one
1746	// side. Plain `quantize` keeps them apart and in the right order.
1747	#[test]
1748	fn a_sixteen_color_terminal_gets_one_bevel_edge_and_not_two() {
1749	for (id, source) in embedded_themes() {
1750	let theme = parse_theme_str(id, source, false).unwrap();
1751	let t = resolve(&theme);
1752	let (Some(face), Some(light), Some(dark)) = (
1753	t.hex("surface-raised").and_then(Rgb::from_hex),
1754	t.hex("bevel-light").and_then(Rgb::from_hex),
1755	t.hex("bevel-dark").and_then(Rgb::from_hex),
1756	) else {
1757	continue;
1758	};
1759
1760	let face_index = quantize(face, &ANSI_16);
1761	let light_survives = quantize(light, &ANSI_16) != face_index;
1762	let dark_survives = quantize(dark, &ANSI_16) != face_index;
1763	assert!(
1764	light_survives != dark_survives,
1765	"{id}: expected exactly one bevel edge to survive 16 colors, \
1766	highlight {light_survives} shadow {dark_survives}"
1767	);
1768
1769	// Direction-blind, so it collapses the pair it is asked to separate.
1770	assert_eq!(
1771	quantize_against(light, face, &ANSI_16),
1772	quantize_against(dark, face, &ANSI_16),
1773	"{id}: quantize_against is expected to be unusable for a bevel pair"
1774	);
1775	}
1776	}
1777
1778	// 256 colors is where the bevel starts working. At 16 every shipped theme
1779	// loses an edge; here all but the five whose raised surface sits at the very
1780	// top of the ramp keep both, and those five fail for the reason they fail in
1781	// truecolor rather than for a palette reason.
1782	//
1783	// Three of them cannot bevel at any depth, so they are the
1784	// `bevel_edges_are_distinct_from_their_face` set. The other two are new here:
1785	// they hold a highlight in 24-bit, but not one wide enough to survive
1786	// rounding onto the cube.
1787	#[test]
1788	fn two_hundred_fifty_six_colors_keep_both_bevel_edges() {
1789	const LOSES_AN_EDGE: &[&str] = &[
1790	"gruvbox-light",
1791	"neobrute",
1792	"oxocarbon-light",
1793	"rosepine-dawn",
1794	];
1795
1796	let mut lost: Vec<String> = Vec::new();
1797	for (id, source) in embedded_themes() {
1798	let theme = parse_theme_str(id, source, false).unwrap();
1799	let t = resolve(&theme);
1800	let (Some(face), Some(light), Some(dark)) = (
1801	t.hex("surface-raised").and_then(Rgb::from_hex),
1802	t.hex("bevel-light").and_then(Rgb::from_hex),
1803	t.hex("bevel-dark").and_then(Rgb::from_hex),
1804	) else {
1805	continue;
1806	};
1807
1808	// Against the fixed region, which is what a consumer should use: a
1809	// match in the low sixteen is a match against a repaintable color.
1810	let f = quantize(face, ANSI_240);
1811	let l = quantize(light, ANSI_240);
1812	let d = quantize(dark, ANSI_240);
1813	if l == f \|\| d == f \|\| l == d {
1814	lost.push(id.to_string());
1815	}
1816	}
1817	lost.sort();
1818
1819	assert_eq!(
1820	lost, LOSES_AN_EDGE,
1821	"themes that cannot hold a two-tone bevel on a 256-color terminal"
1822	);
1823	}
1824
1825	#[test]
1826	fn the_256_table_has_its_three_regions() {
1827	// Index is the escape-sequence index, so the low sixteen must match.
1828	assert_eq!(ANSI_256[..16], ANSI_16);
1829	// The cube's corners, at both ends and one interior level.
1830	assert_eq!(ANSI_256[16].tuple(), (0, 0, 0));
1831	assert_eq!(ANSI_256[231].tuple(), (255, 255, 255));
1832	assert_eq!(ANSI_256[16 + 36 * 2 + 6 * 3 + 4].tuple(), (135, 175, 215));
1833	// The gray ramp runs 8 to 238 and contains neither black nor white.
1834	assert_eq!(ANSI_256[232].tuple(), (8, 8, 8));
1835	assert_eq!(ANSI_256[255].tuple(), (238, 238, 238));
1836	// The fixed region is the table minus the repaintable colors.
1837	assert_eq!(ANSI_240.len(), 240);
1838	assert_eq!(ANSI_240[0], ANSI_256[ANSI_240_OFFSET]);
1839	}
1840
1841	#[test]
1842	fn resolve_overlay_is_dark_translucent_scrim() {
1843	let theme = parse_theme_str("nord", nord_toml(), false).unwrap();
1844	let t = resolve(&theme);
1845	let overlay = t.hex("overlay").unwrap();
1846	assert!(
1847	overlay.starts_with("rgba("),
1848	"overlay is translucent: {overlay}"
1849	);
1850	assert!(overlay.ends_with(", 0.5)"));
1851	// The scrim tone is anchored very dark regardless of theme.
1852	let inner = overlay
1853	.trim_start_matches("rgba(")
1854	.trim_end_matches(", 0.5)");
1855	let parts: Vec<u8> = inner.split(", ").map(\|p\| p.parse().unwrap()).collect();
1856	let scrim = Rgb {
1857	r: parts[0],
1858	g: parts[1],
1859	b: parts[2],
1860	};
1861	assert!(scrim.to_oklab().l < 0.2, "scrim must be near-black");
1862	}
1863
1864	#[test]
1865	fn resolve_drops_non_hex_base_intent() {
1866	// A base intent that isn't a hex color must never reach the resolved
1867	// token set (it would otherwise be inlined verbatim into a <style>
1868	// block). Skipped like a missing intent; valid siblings survive.
1869	let theme = parse_theme_str(
1870	"x",
1871	"[surface]\npage = \"</style><script>alert(1)</script>\"\n[content]\nprimary = \"#111111\"\n",
1872	false,
1873	)
1874	.unwrap();
1875	let t = resolve(&theme);
1876	assert!(
1877	t.hex("surface-page").is_none(),
1878	"non-hex base intent leaked"
1879	);
1880	assert_eq!(t.hex("content").unwrap(), "#111111");
1881	// The injected markup appears in no resolved value.
1882	assert!(!t.intents.values().any(\|v\| v.contains('<')));
1883	}
1884
1885	#[test]
1886	fn resolve_skips_derived_when_source_missing() {
1887	// No [action] => no action-derived tokens.
1888	let theme = parse_theme_str(
1889	"x",
1890	"[surface]\npage = \"#000000\"\n[line]\nborder = \"#222222\"\n",
1891	false,
1892	)
1893	.unwrap();
1894	let t = resolve(&theme);
1895	assert!(t.hex("action").is_none());
1896	assert!(t.hex("action-hover").is_none());
1897	assert!(t.hex("selection").is_none());
1898	assert_eq!(
1899	t.hex("border-strong").unwrap(),
1900	darken(Rgb::from_hex("#222222").unwrap(), 0.05).to_hex()
1901	);
1902	}
1903
1904	#[test]
1905	fn rgb_accessor_for_native_consumers() {
1906	let theme = parse_theme_str("nord", nord_toml(), false).unwrap();
1907	let t = resolve(&theme);
1908	assert_eq!(t.rgb("action"), Some((0x81, 0xa1, 0xc1)));
1909	assert_eq!(t.rgb("nonexistent"), None);
1910	}
1911
1912	// ---- css emit ----
1913
1914	#[test]
1915	fn intent_css_vars_wraps_root_and_includes_tokens() {
1916	let theme = parse_theme_str("nord", nord_toml(), false).unwrap();
1917	let css = intent_css_vars(&resolve(&theme));
1918	assert!(css.starts_with(":root {\n"));
1919	assert!(css.contains(" --surface-page: #2e3440;\n"));
1920	assert!(css.contains(" --danger: #bf616a;\n"));
1921	assert!(css.contains(" --action-hover: "));
1922	assert!(css.trim_end().ends_with('}'));
1923	}
1924
1925	// ---- loading / fs ----
1926
1927	#[test]
1928	fn load_and_resolve_round_trip() {
1929	let dir = tempfile::tempdir().unwrap();
1930	fs::write(dir.path().join("nord.toml"), nord_toml()).unwrap();
1931	let dirs = vec![(dir.path().to_path_buf(), false)];
1932	let t = load_semantic(&dirs, "nord").unwrap();
1933	assert_eq!(t.meta.name, "Nord");
1934	assert_eq!(t.hex("action"), Some("#81a1c1"));
1935	}
1936
1937	#[test]
1938	fn load_theme_rejects_invalid_id() {
1939	assert!(load_theme(&[], "../evil").is_err());
1940	}
1941
1942	fn meta(id: &str, variant: &str) -> ThemeMeta {
1943	ThemeMeta {
1944	id: id.to_string(),
1945	name: id.to_string(),
1946	variant: variant.to_string(),
1947	is_custom: false,
1948	}
1949	}
1950
1951	fn defaults() -> ThemeDefaults {
1952	ThemeDefaults::new("flatwhite", "nord")
1953	}
1954
1955	// The three the shipped themes actually declare.
1956	#[test]
1957	fn every_shipped_variant_parses() {
1958	assert_eq!(Variant::parse("light"), Some(Variant::Light));
1959	assert_eq!(Variant::parse("dark"), Some(Variant::Dark));
1960	assert_eq!(Variant::parse("high-contrast"), Some(Variant::HighContrast));
1961	assert_eq!(Variant::parse("sepia"), None);
1962	}
1963
1964	// parse_meta already defaults a missing variant to dark, so an
1965	// unrecognized one reading as light would have the crate disagreeing with
1966	// itself. alloy_tui did exactly that before this existed.
1967	#[test]
1968	fn an_unrecognized_variant_reads_the_way_a_missing_one_does() {
1969	assert_eq!(Variant::from("sepia"), Variant::Dark);
1970	assert_eq!(Variant::from(""), Variant::Dark);
1971
1972	let missing: toml::Table = "[meta]\nname = \"X\"\n".parse().unwrap();
1973	assert_eq!(parse_meta("x", &missing, false).kind(), Variant::Dark);
1974	}
1975
1976	#[test]
1977	fn a_selection_round_trips_through_any_store() {
1978	for (stored, expect) in [
1979	(Some("system"), ThemeSelection::Follow),
1980	(None, ThemeSelection::Follow),
1981	(Some(""), ThemeSelection::Follow),
1982	(Some(" "), ThemeSelection::Follow),
1983	(Some("nord"), ThemeSelection::Fixed("nord".into())),
1984	] {
1985	let parsed = ThemeSelection::parse(stored);
1986	assert_eq!(parsed, expect, "{stored:?}");
1987	assert_eq!(
1988	ThemeSelection::parse(Some(parsed.as_str())),
1989	expect,
1990	"what is written reads back as what was meant",
1991	);
1992	}
1993	}
1994
1995	// Nothing saved is follow-the-system, which is what Balanced Breakfast
1996	// expressed as an absent value and GoingsOn as a sentinel. Both are now the
1997	// same thing.
1998	#[test]
1999	fn nothing_chosen_yet_is_follow() {
2000	assert_eq!(ThemeSelection::default(), ThemeSelection::Follow);
2001	}
2002
2003	#[test]
2004	fn a_fixed_selection_wins_when_its_theme_is_installed() {
2005	let available = [meta("nord", "dark"), meta("flatwhite", "light")];
2006	let fixed = ThemeSelection::Fixed("nord".into());
2007	assert_eq!(
2008	fixed.resolve(Variant::Light, &defaults(), &available),
2009	"nord",
2010	"a chosen theme is not overridden by the ambient mode",
2011	);
2012	}
2013
2014	// Themes are deletable in three of the four apps. Handing back an id that
2015	// will fail to load only moves the error somewhere less helpful.
2016	#[test]
2017	fn a_fixed_selection_whose_theme_is_gone_falls_back() {
2018	let available = [meta("nord", "dark"), meta("flatwhite", "light")];
2019	let fixed = ThemeSelection::Fixed("deleted".into());
2020	assert_eq!(
2021	fixed.resolve(Variant::Light, &defaults(), &available),
2022	"flatwhite",
2023	);
2024	}
2025
2026	#[test]
2027	fn follow_picks_the_apps_default_for_the_ambient_mode() {
2028	let available = [meta("nord", "dark"), meta("flatwhite", "light")];
2029	let follow = ThemeSelection::Follow;
2030	assert_eq!(
2031	follow.resolve(Variant::Dark, &defaults(), &available),
2032	"nord",
2033	);
2034	assert_eq!(
2035	follow.resolve(Variant::Light, &defaults(), &available),
2036	"flatwhite",
2037	);
2038	}
2039
2040	// The behaviour Balanced Breakfast could not have: following the system
2041	// into a theme the user installed, when the app's own default is absent.
2042	#[test]
2043	fn follow_uses_any_installed_theme_of_the_right_variant() {
2044	let available = [meta("solarized-light", "light"), meta("mine", "dark")];
2045	assert_eq!(
2046	ThemeSelection::Follow.resolve(Variant::Dark, &defaults(), &available),
2047	"mine",
2048	"the app's `nord` is not installed, but a dark theme is",
2049	);
2050	}
2051
2052	// Always returns something: an app with no theme directory gets the id it
2053	// ships with, and the load error it would have had anyway.
2054	#[test]
2055	fn an_empty_catalog_still_names_the_apps_default() {
2056	assert_eq!(
2057	ThemeSelection::Follow.resolve(Variant::Dark, &defaults(), &[]),
2058	"nord",
2059	);
2060	}
2061
2062	#[test]
2063	fn high_contrast_falls_back_to_dark_unless_named() {
2064	let plain = defaults();
2065	assert_eq!(plain.for_variant(Variant::HighContrast), "nord");
2066
2067	let named = defaults().high_contrast("sharp");
2068	assert_eq!(named.for_variant(Variant::HighContrast), "sharp");
2069	}
2070
2071	// The bug this builder exists to prevent: the Alloy console pushed the
2072	// user's directory first under a comment reading "highest precedence
2073	// first", when both consumers of this vector resolve last-wins. A custom
2074	// theme lost to the packaged one of the same id.
2075	#[test]
2076	fn the_users_own_themes_outrank_everything() {
2077	let root = tempfile::tempdir().unwrap();
2078	let make = \|name: &str\| {
2079	let dir = root.path().join(name);
2080	std::fs::create_dir_all(&dir).unwrap();
2081	dir
2082	};
2083	let (bundled, system, custom) = (make("bundled"), make("system"), make("custom"));
2084
2085	let dirs = ThemeDirs::new()
2086	.custom(Some(custom.clone()))
2087	.bundled(Some(bundled.clone()))
2088	.system(Some(system.clone()))
2089	.build();
2090
2091	assert_eq!(
2092	dirs,
2093	vec![(bundled, false), (system, false), (custom.clone(), true)],
2094	"lowest precedence first, whatever order the tiers were added in",
2095	);
2096	assert!(dirs.last().unwrap().1, "only the user's tier is custom");
2097
2098	// And the ordering means what the consumers think it means.
2099	for dir in dirs.iter().map(\|(dir, _)\| dir) {
2100	std::fs::write(dir.join("shared.toml"), "[meta]\nname = \"x\"\n").unwrap();
2101	}
2102	assert_eq!(
2103	find_theme_path(&dirs, "shared").unwrap().0,
2104	custom.join("shared.toml"),
2105	"the user's copy is the one that loads",
2106	);
2107	}
2108
2109	#[test]
2110	fn a_directory_that_does_not_exist_is_dropped() {
2111	let root = tempfile::tempdir().unwrap();
2112	let real = root.path().join("real");
2113	std::fs::create_dir_all(&real).unwrap();
2114
2115	let dirs = ThemeDirs::new()
2116	.bundled(Some(root.path().join("nope")))
2117	.system(None)
2118	.custom(Some(real.clone()))
2119	.build();
2120
2121	assert_eq!(dirs, vec![(real, true)]);
2122	}
2123
2124	// A Tauri app has two bundled tiers: the resource dir in production and the
2125	// tree build.rs materialized for a dev run with no resource dir.
2126	#[test]
2127	fn more_than_one_bundled_tier_is_allowed() {
2128	let root = tempfile::tempdir().unwrap();
2129	let (first, second) = (root.path().join("a"), root.path().join("b"));
2130	std::fs::create_dir_all(&first).unwrap();
2131	std::fs::create_dir_all(&second).unwrap();
2132
2133	let dirs = ThemeDirs::new()
2134	.bundled(Some(first.clone()))
2135	.bundled(Some(second.clone()))
2136	.build();
2137	assert_eq!(dirs, vec![(first, false), (second, false)]);
2138	}
2139
2140	#[test]
2141	fn list_themes_from_dirs_finds_toml_files() {
2142	let dir = tempfile::tempdir().unwrap();
2143	fs::write(dir.path().join("t.toml"), "[meta]\nname = \"T\"\n").unwrap();
2144	fs::write(dir.path().join("x.txt"), "ignored").unwrap();
2145	let dirs = vec![(dir.path().to_path_buf(), false)];
2146	let themes = list_themes_from_dirs(&dirs);
2147	assert_eq!(themes.len(), 1);
2148	assert_eq!(themes[0].id, "t");
2149	}
2150
2151	#[test]
2152	fn find_theme_path_reverse_priority() {
2153	let d1 = tempfile::tempdir().unwrap();
2154	let d2 = tempfile::tempdir().unwrap();
2155	fs::write(d1.path().join("s.toml"), "[meta]\n").unwrap();
2156	fs::write(d2.path().join("s.toml"), "[meta]\n").unwrap();
2157	let dirs = vec![
2158	(d1.path().to_path_buf(), false),
2159	(d2.path().to_path_buf(), true),
2160	];
2161	let (path, is_custom) = find_theme_path(&dirs, "s").unwrap();
2162	assert!(is_custom);
2163	assert_eq!(path, d2.path().join("s.toml"));
2164	}
2165
2166	#[test]
2167	fn import_theme_valid_and_rejects_empty() {
2168	let src_dir = tempfile::tempdir().unwrap();
2169	let custom_dir = tempfile::tempdir().unwrap();
2170
2171	let good = src_dir.path().join("my-theme.toml");
2172	fs::write(&good, "[surface]\npage = \"#1a1b26\"\n").unwrap();
2173	let meta = import_theme(&good, custom_dir.path()).unwrap();
2174	assert_eq!(meta.id, "my-theme");
2175	assert!(custom_dir.path().join("my-theme.toml").exists());
2176
2177	let empty = src_dir.path().join("empty.toml");
2178	fs::write(&empty, "[meta]\nname = \"E\"\n").unwrap();
2179	assert!(import_theme(&empty, custom_dir.path()).is_err());
2180	}
2181
2182	#[test]
2183	fn import_theme_rejects_invalid_toml() {
2184	let src_dir = tempfile::tempdir().unwrap();
2185	let custom_dir = tempfile::tempdir().unwrap();
2186	let src = src_dir.path().join("bad.toml");
2187	fs::write(&src, "this is not [valid toml [[[").unwrap();
2188	assert!(import_theme(&src, custom_dir.path()).is_err());
2189	}
2190
2191	#[test]
2192	fn delete_theme_removes_and_guards() {
2193	let custom = tempfile::tempdir().unwrap();
2194	let path = custom.path().join("doomed.toml");
2195	fs::write(&path, "[surface]\npage = \"#000\"\n").unwrap();
2196	delete_theme(custom.path(), "doomed").unwrap();
2197	assert!(!path.exists());
2198	assert!(delete_theme(custom.path(), "../etc/passwd").is_err());
2199	assert!(delete_theme(custom.path(), "ghost").is_err());
2200	}
2201
2202	#[test]
2203	fn export_theme_copies_file() {
2204	let src_dir = tempfile::tempdir().unwrap();
2205	let dest_dir = tempfile::tempdir().unwrap();
2206	let content = "[meta]\nname = \"E\"\n[surface]\npage = \"#ffffff\"\n";
2207	fs::write(src_dir.path().join("e.toml"), content).unwrap();
2208	let dirs = vec![(src_dir.path().to_path_buf(), false)];
2209	let dest = dest_dir.path().join("out.toml");
2210	export_theme(&dirs, "e", &dest).unwrap();
2211	assert_eq!(fs::read_to_string(&dest).unwrap(), content);
2212	assert!(export_theme(&dirs, "missing", &dest).is_err());
2213	}
2214
2215	#[test]
2216	fn load_theme_preview_returns_role_swatches() {
2217	let dir = tempfile::tempdir().unwrap();
2218	fs::write(dir.path().join("nord.toml"), nord_toml()).unwrap();
2219	let dirs = vec![(dir.path().to_path_buf(), false)];
2220	let p = load_theme_preview(&dirs, "nord").unwrap();
2221	assert_eq!(p.background.as_deref(), Some("#2e3440")); // surface.page
2222	assert_eq!(p.foreground.as_deref(), Some("#d8dee9")); // content.primary
2223	assert_eq!(p.accent.as_deref(), Some("#81a1c1")); // action.primary
2224	assert_eq!(p.border.as_deref(), Some("#4c566a")); // line.border
2225	}
2226
2227	#[test]
2228	fn bundled_themes_dir_resolves_to_shipped_themes() {
2229	// The crate ships its themes, so this must resolve in-tree and the
2230	// Akari defaults the console falls back to must be present.
2231	let dir = bundled_themes_dir().expect("makeover ships a themes/ directory");
2232	assert!(dir.join("akari-dawn.toml").is_file());
2233	assert!(dir.join("akari-night.toml").is_file());
2234	}
2235
2236	#[test]
2237	fn every_theme_is_accounted_for_in_third_party_notices() {
2238	// Attribution is a redistribution obligation, not a nicety: adding a
2239	// theme without a notice entry silently ships someone's work
2240	// uncredited. Fail here instead.
2241	let notices = std::fs::read_to_string(
2242	Path::new(env!("CARGO_MANIFEST_DIR")).join("THIRD-PARTY-NOTICES.md"),
2243	)
2244	.expect("THIRD-PARTY-NOTICES.md must exist");
2245	let missing: Vec<&str> = embedded_themes()
2246	.map(\|(id, _)\| id)
2247	.filter(\|id\| !notices.contains(*id))
2248	.collect();
2249	assert!(
2250	missing.is_empty(),
2251	"themes missing from THIRD-PARTY-NOTICES.md: {missing:?}"
2252	);
2253	}
2254
2255	#[test]
2256	fn adapted_themes_carry_inline_attribution() {
2257	// Each adapted file must name its upstream in-file, so the credit
2258	// survives someone copying a single .toml out of the crate.
2259	const ORIGINALS: [&str; 5] = [
2260	"makenotwork",
2261	"goingson",
2262	"audiofiles",
2263	"high-contrast",
2264	"neobrute",
2265	];
2266	for (id, source) in embedded_themes() {
2267	if ORIGINALS.contains(&id) {
2268	continue;
2269	}
2270	assert!(
2271	source.contains("adapted from"),
2272	"adapted theme `{id}` is missing its inline attribution header"
2273	);
2274	}
2275	}
2276
2277	#[test]
2278	fn embedded_themes_match_the_directory() {
2279	// The embedded copy and themes/ are two views of one source. If they
2280	// ever disagree, path-based and path-free consumers render different
2281	// theme sets, which is exactly the drift shipping the data was meant
2282	// to prevent.
2283	let dir = bundled_themes_dir().unwrap();
2284	let mut on_disk: Vec<String> = std::fs::read_dir(&dir)
2285	.unwrap()
2286	.filter_map(\|e\| {
2287	let path = e.ok()?.path();
2288	if path.extension()? != "toml" {
2289	return None;
2290	}
2291	Some(path.file_stem()?.to_str()?.to_string())
2292	})
2293	.collect();
2294	let mut embedded: Vec<String> = embedded_themes().map(\|(id, _)\| id.to_string()).collect();
2295	on_disk.sort();
2296	embedded.sort();
2297	assert_eq!(embedded, on_disk, "embedded theme set drifted from themes/");
2298	}
2299
2300	#[test]
2301	fn every_embedded_theme_parses() {
2302	// Guards the path-free consumers (MNW server, the Tauri build steps)
2303	// the same way every_shipped_theme_loads guards the path-based ones.
2304	let mut count = 0;
2305	for (id, source) in embedded_themes() {
2306	parse_theme_str(id, source, false)
2307	.unwrap_or_else(\|e\| panic!("embedded theme `{id}` failed to parse: {e}"));
2308	count += 1;
2309	}
2310	assert!(count >= 30, "expected the full theme set, got {count}");
2311	}
2312
2313	#[test]
2314	fn every_shipped_theme_loads() {
2315	// Guards the data, not just the loader: a malformed or truncated
2316	// .toml in themes/ is a shipping bug, and it should fail here rather
2317	// than at a user's first launch.
2318	let dir = bundled_themes_dir().unwrap();
2319	let dirs = vec![(dir.clone(), false)];
2320	let themes = list_themes_from_dirs(&dirs);
2321	assert!(
2322	themes.len() >= 30,
2323	"expected the full theme set, got {}",
2324	themes.len()
2325	);
2326	for meta in &themes {
2327	load_theme(&dirs, &meta.id)
2328	.unwrap_or_else(\|e\| panic!("shipped theme `{}` failed to load: {e}", meta.id));
2329	}
2330	}
2331	}
2332